INTEODUCTION. 
The Preliminary Reports on the Echini of the BUike Expeditions for 
1877-78, for 1878-79, and for the summer of 1880, were published in Vol. 
v.. No. 9, Bull. M. C. Z., and Vol. VIIL, No. 2, Bull. M. C. Z. In the former 
Report will be foimd all the Stations occupied in the Gulf of Mexico and 
Straits of Florida : in the latter, the Stations explored along the West India 
Islands and the Atlantic coast of the United States. I give in this Report, 
therefore, only principal localities in sufficient number to indicate the geo- 
graphical range and bathymetrical distribution of each species as determined 
by the dredgings of the " Blake." In the Report on the Echini of the 
Challenger Expedition I have given a list of the bathymetrical and geo- 
graphical distribution of all the species of Echini then known, including the 
species collected by the Blake Expeditions. The Preliminary Reports on the 
Deep-sea Echini, collected by Mr. Pourtales off the Florida Reefs, were 
published in the Bull. M. C. Z., Vol. I., No. 9. The final Report was incor- 
porated in Part II. of the Revision of the Echini under the name of " East 
Coast Echini," 111. Cat. M. C. Z., No. VII. Mem. M. C. Z., Vol. III., 1872-74. 
The importance of the collection of the Echini brought together during 
the cruises of the " Blake " is well shown by a comparative statement of our 
knowledge of the Caribbean Echinid Fauna before and after the explorations 
undertaken under the auspices of the United States Coast Survey. 
There are now known eighty-three species of Sea-urchins from the Carib- 
bean Fauna. Of these, eleven were added by the dredgings of Count 
Pourtales in the "Bibb" and " Hassler," nineteen were discovered by the 
" Blake," and thirteen species previously known from other districts were 
dredged for the first time in the Caribbean and adjoining seas by the Coast 
